1. Field of the Invention
The present invention relates to media copy protection, and more particularly, to digital media copy management method and system that control each copy generation process and prevent any unauthorized (illegal) digital media data copy.
2. Discussion of the Related Art
Watermarking is a technology, in which copyright information (information indicating a copy guard) is expressed by a watermark superposed in media data. Such information is embedded into various media data including image data and sound data, and it should be invisible and inaudible to a human observer. The purpose of superposing a watermark in the media data is to provide a proof of a copyright so that an illegal use and copy of the media data can be prevented. Therefore, the copyright information should stay stable in a host signal even when the host signal is subjected to any data process.
The technique for superposing a watermark in the media data depends on the size of the watermark data and the invariance of the watermark data to any data process of a host signal. There is a watermark inherent trade-off between the human perceptibility, bandwidth, and robustness (i.e., the degree to which the data are immune to be attacked or transformations that occur to the host signal through a normal usage). The more data to be superposed, the less secure the encoding process is. The less data to be superposed, the more secure the encoding process is.
The currently existing solutions for the media data protection and data copy control do not fully eliminate or significantly reduce digital media piracy. Therefore, it is essential that a new protection technology should be provided.